This invention relates to a compact, audio, tape cassette and, more particularly, to a self-locking hub assembly for such a tape cassette which prevents despooling of the recording tape when the tape cassette is not engaged with a tape player/recorder.
A conventional, compact, audio, tape cassette contains two hubs onto which the tape is wound for supply and take-up during operation. These hubs are located between the tape cassette cover and base and are contained radially by pairs of raised annular rings formed on the inside surfaces of the cover and base which engage recessed rings on the top and bottom surfaces of each hub. When engaged with a tape player/recorder, a finned spindle thereof enters the center of the hub and cooperates with spokes formed on the center of the hub to permit a driven clockwise or counterclockwise motion of the hubs.
Because of industry tolerances, the spindles of one manufacturer's tape player/recorder can be as much as 1/32 inch different in relative location (closer or further apart) than those of another manufacturer. It is, therefore, necessary to create a clearance between the recessed rings formed on the hubs and the raised annular rings formed on the tape cassette cover and base. This clearance, however, means that, when a tape cassette is disengaged from the tape player/recorder, the hubs can turn freely and "despool," i.e., allow tape to spill throughout the inside of the tape cassette. Such despooling is not desirable because tape damage and jam conditions can result.
In order to prevent despooling, manufacturers of compact, audio, tape cassettes, an example of which is shown in FIG. 1 herein and referred to generally by reference numeral 10, currently use a separate, elongated clip 12 having perpendicular hooks 14 and 16 at the ends thereof which are manually inserted into the centers 18 and 20 of the tape reel hubs 22 and 24, respectively. The clip 12 is relatively simple, inexpensive and requires little work to apply after the tape cassette 10 is assembled. As a result, such clips 12 have gained widespread acceptance in the compact, audio, tape cassette industry. Unfortunately, however, the consumer ultimately removes the clip 12 to use the tape cassette 10 and usually discards the clip 12, which again results in despooling during subsequent handling.
In arts other than the compact, audio, tape cassette art, efforts have also been made to prevent despooling. For example, U.S. Pat. No. 3,066,880, issued to BAUER, describes a self-locking hub assembly for a single reel tape cartridge, which is shown in FIGS. 2 and 3 herein. More particularly, an axially and radially extending slot 30 is formed in the hub 32 to receive a movable member 34 for releasably coupling the hub 32 to the cartridge 36. The movable member 34 is pivotally mounted on a pin 38 extending across the slot 30 for angular movement relative to the plane of the hub 32. The movable member 34 includes a detent portion 40 which is normally urged by a spring 42 upwards toward the cartridge portion 44 to be received in any one of a plurality of radially extending slots 46 formed in the inside wall of the cartridge portion 44. The movable member 34 also has an actuator portion 48 which can extend inwardly from the inside wall 50 of the hub 32. Upon engaging the cartridge 36 with a tape player/recorder (not shown), the spindle 52 thereof causes the movable member 34 to rotate, which moves the actuator portion 48 outwardly and releases the hub 34 from the cartridge 36 so that the tape (not shown) can be supplied and taken up under the control of the spindle 52.
The self-locking hub assembly described in the '880 patent provides suitable self-locking for a single reel tape cartridge, but is not applicable to a double reel, compact, audio, tape cassette. As evidence, although the teaching of the '880 patent has been available for almost twenty-five years and compact, audio, tape cassettes have been available at least for twenty years (see U.S. Pat. No. 3,394,899, issued to SCHOENMAKERS), no one has successfully incorporated the type of self-locking hub assembly taught by the '880 patent into a compact, audio, tape cassette--the reasons follow.
First, the pivoting nature of the self-locking hub assembly of the '880 patent works only when the single reel tape cartridge is inserted into the tape player/recorder in the one direction shown in FIG. 3 herein. If an attempt is made to insert the single reel tape cartridge 36 in the opposite direction, the movable member 34 would immovably abut the spindle 52 and prevent insertion of the cartridge 36 into the tape player/recorder. Compact, audio, tape cassettes, on the other hand, are intentionally reversible, i.e., are designed to be inserted into the tape player/recorder from two distinct directions, the top first or bottom first, to play both "sides" or "tracks" of the tape. As a result, if the self-locking hub assembly of the '880 patent was used in a compact, audio, tape cassette, it might be capable of locking the hub when the cassette was not engaged with the tape player/recorder; however, unlocking of the hub and operation of the tape cassette would be impossible when inserted in a second direction.
Second, the self-locking hub described in the '880 patent requires enough vertical space in the cartridge to incorporate at least one opening 46, the movable member 34, the pivot pin 38 and the spring 42. In addition, the movable member 34 must have enough room to pivot up and down in order to operate. In a compact, audio, tape cassette, space is very limited. For example, a self-locking hub assembly would have to occupy only about 155 to 165 thousandths of an inch. As a result, a compact, audio, tape cassette could not incorporate the several members or the pivoting, angular motion required by the self-locking hub assembly of the '880 patent. Further, in light of the limited ability to insert the device of the '880 patent in only one direction, if one were to attempt to make the movable member 34 pivot in opposite directions to allow insertion of the cassette top first or bottom first, more components and more space would be required, which a compact, audio, tape cassette could not accommodate.
Third, relatively complicated assembly of the pivoting device of the self-locking hub of the '880 patent in a compact, audio, tape cassette is prohibited by the mere nature of compact, audio, tape cassette manufacturing, wherein speedy, simple and low cost, mass production are critical.
In light of the above, a more efficient and easier to assemble self-locking hub assembly for a compact, audio, tape cassette is desired, which prevents the hubs from rotating whenever the cassette is not engaged with a tape player/recorder, but allows easy release of the hubs, when the cassette is inserted in either direction into a tape player/recorder. A faster and easier method for assembling a self-locking hub assembly is also desired.